I've wondered about airport security/customs dogs in the past. I had one go nuts on my purse one time at the Bangkok airport; turned out the dog was interested in a packet of cookies that I had (and not ones with poppy seeds or anything, either). I always wondered how the dog could be trained to be (one would expect) so disciplined as to detect and alert on drugs, yet was alerting on something as common as snack foods as well. Then years later I dealt professionally with several people who had been arrested by US customs as drug couriers. More than one of them mentioned customs dogs being led right by them (in the source countries' airports) while they had large quantities of real drugs on them without the dogs seeming the least bit interested. One gentleman had flown out of Peru with cocaine taped all over his body under his clothes, and, while awaiting his flight in the Peruvian airport lounge, had had a customs dog handler sit down in the chair next to him, and the dog lay down beside him on the floor, never alerting on a thing.

So this case clears up a few questions for me. Honestly never occurred to me that dogs might be being trained to alert on anything, or to alert only on command. Seems like it would be a lot cheaper for law enforcement to train the dogs that way, too.

The dogs are supposed to have a seek command and usually the handler guides their motion tapping as much as he can to expel a bit of air out of luggage or envelopes or whatnot.

Handlers often misinterpret signals and often the "alert" signal is for the dog to sit down.... well, dogs sit down when tired or bored too.

Handlers are supposed to give the dog a toy as a reward and later exchange the toy for food.

Drug mules are usually fools. Often the person sending drugs into a country will send in a mule or two as a "bone" to that country's customs officers. So some mules are guaranteed to be imprisoned.

Long ago a craps shooter had his dog and his sighted companion with him when the dog became interested in the craps dealer. While exchanging idle conversation the dealer asked where did you get your dog... and then immediately asked to be tapped out when the owner replied "He is retired from the LAPD". When he tapped back in, the box asked him "is it gone?".

Back when I used to smoke, I had a big ol' bag of stink on me while walking around the County Fair. Since stoners aren't exactly bright, I hit every exhibit, including all those of law enforcement. Hey, doggies! I wanna pet one!

Wasn't til I saw about the third DEA shirt that it hit me. Not a single dog paid me any bit of notice.

Drug mules are usually fools. Often the person sending drugs into a country will send in a mule or two as a "bone" to that country's customs officers. So some mules are guaranteed to be imprisoned.

You're completely right, and you've brought up something that I learned at that job that surprised me: Drug couriers are not the smugglers. The drug trafficking organizations deliberately hire mules to create a false profile. If law enforcement can be led to believe that the people bringing drugs into the country are white twentysomethings travelling by air, then law enforcement will (hopefully, at least from the organization's point of view) be less likely to target latino fishing boat captains in their forties and fifties (who do the bulk of the actual smuggling).

Sometimes (often? usually?), the drug trafficking organization itself will tip off customs about who they've sent with loads of drugs taped under their clothes or secreted in their luggage or their stomachs. Partially because of the desire to create a false profile that I mentioned above, but also (at least occasionally) so that customs will be too busy dealing with the two foreigners set up by the organization to notice that everyone else on the flight had drugs, too. Again, this is all just what I understand from people I've had to deal with and reports that I've read; I've never worked for such an organization myself and so could be completely wrong. But I thought that it was all pretty interesting, at least in part because, prior to that assignment, I had always figured that the mules with drugs taped under their clothes and secreted within their bodies were the way that drugs come into the country.